Field deformation and loss caused by curvature of optical fibers

Abstract

Curvature loss formulas of optical fibers usually ignore the effect of field deformation caused by the curved axis of the fiber. Contrary to naive intuition, this field deformation may substantially decrease the radiation losses of modes with low mode number. Losses of modes with high mode numbers are, however, increased. We present a theoretical evaluation of curvature losses of the modes of a step-index fiber with a bent axis incorporating the influence of field deformation on the loss coefficient. The limitations of the simple loss formula in case of a sharply bent overmoded waveguide are pointed out.